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These feature articles are published monthly by Quality Digest. They are collected under the nom de plume of The Six Sigma Heretic, which tells you something about how we approach Six Sigma. They are written by ROI President Steven Ouellette, and have a unique blend of humor and statistical depth that makes him one of Quality Digest's most popular authors. Subscribe to our RSS Feed to be alerted about each month's article!

Choosing the Right Material (finally!)

If you have been following my articles for the last few months, you know that we’re almost done with an experimental analysis and that today we will be doing the final step—making our company money. If you haven’t been following my articles, then you should probably be flogged with a soggy noodle until you admit to your other crimes in a tearful confession posted on YouTube.

Nothing to be afraid of

For the last couple of columns, we have been analyzing a simple experiment where we look for the best choice for a new gear material. We have used analysis of variance (ANOVA) to detect a difference in the mean wear for the four different materials. In the last column, we performed a post-hoc test to determine which means were actually different from one another. However, to find the best solution, we need to know true costs, and to get that I need to know the variability associated with the different materials. At the end of the article, I’ll give you a chance to show off —the first one to e-mail me the correct cost analysis will get bragging rights and their name (or reasonably tasteful nom de plume if you prefer) in print.

If there is a difference, what is it?

Last month, I described a simple problem to determine which gear material resulted in longer wear. We reviewed the extremely powerful technique called Analysis of Variance (ANOVA) and found a statistically significant and important effect on the average wear due to gear material. I also promised to tell you about an infrequently used next step that would make you a lot of money. That is what we are going to talk about this month.

Elegance Rules

By the time you are reading this, you will have made your New Year’s resolutions, and I will have already broken mine. But I have an idea for a resolution that you might be interested in keeping, and one that could make your New Year happy and profitable. It is something that most Black Belts I talk to have never heard of. Before we get there, we need to talk about another powerful tool, with which you may be familiar.

Digging Out From a Data Blizzard

As I’m writing this, our first big snowfall of the year is piling up outside and it is –10°C (15°F). This brings to mind the many times my grandfather told me of how he walked to school in winter uphill (both ways) with no shoes. So I wondered, will I be able to spin the same yarn for my girls and tell them about how much colder it was when I was young? And could granddad have been exaggerating about more than the fish he caught? So (of course) I did what any data-geek would do and downloaded the data. Let’s take a look and see how this time series pertains to Black Belts.